This motor is going in a C2500 Duallie that's been awaiting a new heart for 2 years in November It's a Tow Rig/Daily driver running a 460LE trans and will be running TBI and Dual 425 Impcos. The engine was bought as a "Rebuilt" unit,
but Hornet's had managed to build nests in many places and as the old man is a fussy bugger,
( it's taken almost 12 months to convince him to let me do it!!)
the decision was made to tear it down and start again ,it'll be a basically stock rebuild with a few extras.

Got it into the shed tonight, I have to make some more room to lay parts out etc, and then have to finish Timing belts and rocker gaskets on a POS Camry tomorrow
so the tear down will start on Saturday. I'll be going at it nice and slow as I only had a knee reconstruction 2 weeks ago.

ok here we go, this thread is gunna be a killer if you are on Dial up so be warned!!

First up I'll go through some of the tools you'll need

Perhaps the most important tool you'll need to use in an engine rebuild is a torque wrench, the higher the intended power the more accurate it needs to be.
These ones shown are Kincrome ones I use at work and are fine for an engine like this.
BUT you will need a 3/8 drive one to do the Rod bolts as they are usually only about 25 flbs and a cheaper 1/2 wrench usually starts between 30 and 50 flbs.

Second, you'll need a decent set of sockets, 1/2 or 3/8 is fine with adapters if you don't have both, but you really need 1/2 for head, main bearing bolts and flywheel/crank bolts
for engine stuff, 6 point or six sided sockets are best, unless you have ARP Studs with 12 point nuts.

Next up, while strictly not necessary, these air die grinders are worth their weight in gold,
some of you guys will remember them from my DIY polishing article,
the scotch brite pads are the ducks guts for cleaning off gaskets and silicone!

Another important tool you'll need is a set of bottoming taps, in 1/4", 5/6", 3/8", 7/6"( I think) and 1/2"

Lastly, you'll need a good Quality balancer puller as shown in a later photo, the balancer on Chevs are a interference fit and can be a bugger to get off! some good ones are from ABW or KC Tools, don't buy the supercrap ones, you'll only brake them

As this engine has already been "Rebuilt" the majority of the engine internals here are going to be Re-used
I'm being careful with taking it apart, but even for a stock rebuild, quite often this can be the case.

You'll also want to have a nice clean, clutter free area to lay the parts out on,
and a good trick is to have a few old ice cream containers (or your handbrakes Tupperware containers!) to keep bolts from separate areas separate,
make sure you mark what is what if your new at this.

Ok first up remove any engine accessories & Brackets, this one didn't have any so even better

Next I typically start from the top and work down,
First remove the tappet covers

Next the inlet manifold, again keep the bolts handy

Remove the Rockers, if they're going to be reused, keep the pivots with thier matching rocker,
if you have a flat tappet cam and adjustable rockers, back all the tappets off before removing them

ok, after removing the rockers and then the pushrods, we found our first problem,
these push rods should be in two groups of 8, each group should be all exactly the same length. this would have caused a good miss.

These ones are odd in that they are only 5/16" normally a big block has 3/8" ones.
Always spend a little bit more and buy the best ones that you can afford, ESPECIALLY if you have big Valve springs and Cam.
Remember that you'll also need to get matching guide plates as BBC's have splayed valves

Next Remove the lifters, these were easy to get out as they were new so I only used an O-Ring pick, a bent screwdriver etc also works.

You can use a set of long nosed pliers and grab them inside the relief to pull them up.
Don't be concerned if you can't get them out, just push them up so they are clear of the cam lobes,
if they're that gunked up they'll stay there. we'll get them out later.

If you plan on reusing the cam & lifters, keep the lifters in sequence,
also be careful no to mark the cam lobes.

Ok next we remove the cylinder heads, using a breaker bar,
(Not your torque wrench, it's a precision instrument!!!)
crack each head bolt/stud, start at the outside and work in a circular pattern towards the middle bolts.
Once they are all cracked then remove the bolts.

Have somebody give you a hand to lift the heads off as they are bloody heavy! , they might need to be pried up first to loosen the gasket.
Voila! now we have a "short" motor.

Ok, now we roll it over and remove the sump, Then undo the Oil pump retaining bolt and remove the oil pump,
be careful you don't loose the retaining collar that holds the distributor drive shaft on.
Now this is what happens if you don't seal up an engine when it's stored.
Yup hornets had built a nest up in the oil gallery from the oil pump, we also found others later where the oil pressure sender goes

Ok, next the balancer, if you don't have a rattle gun you can use a Hammer handle or block of wood
(like shown) to jam the crank and undo the retaining bolt.
This is where the puller comes in, Don't use a rattle gun on it either, you'll most likely tear out a thread.
Again jam the crank counterweight and remove the balance using the puller, this one was really tight and I had to use a 24" breaker bar to wind it off.

Now be careful as it comes off, they're pretty heavy too.
I was lucky it missed my toes
As you can see it put a nice divot in the Concrete.
( and my Chinese work boots!!)

To turn the engine over in the next stages you can either use a large shifter ( make sure the jaws are smooth) , or a special crank socket, DON'T use Stilsons or Multi Grips!!

Ok, on to the ConRods & Pistons
Undo the caps, give them a gentle tap to unseat the oil seal and tap the rod down using your block of wood, a brass drift or hammer handle.
Be careful not to let the rod end or rod bolts touch the crank and mark it.
Get your offsider to grab the piston as it comes out, set them aside in numbered order (if you plan to re-use them) for later

Next we remove the timing chain, unlike this engine there should be a flat plate under the bolts holding
the cam sprocket that locks the bolts, using a screwdriver or small cold chisel, prise the tabs out and knock them down flat.
Undo the three bolts and remove the sprocket and chain, leave the one on the crank for now,
also it's a good practice to line up the marks and see where they are for future reference,
not all replacement chains or gears are marked at all or the same and you might need to reference back to it later.

On to the Main caps, Using your breaker bar crack and undo each main bolt/stud.
Then Tap the caps slightly sideways to break the oil seal like shown, you might need to tap them either side a few times,
if you need to give it a whack, use a soft face hammer or a drift so you don't mark the metal.

Lift the crank out and put it aside, now we remove the cam, always a good tool to have is a handle which attaches to front of the cam.
All Chevs are the same, and for Holden V8's you can use a bit of pipe with an old cam bolt welded into it,
I've not gotten around to buying/making one yet so I just got the old man to give me a hand. (The apprentice!! ):lol:
Very carefully ( Especially if you want to re-use the cam and or cam bearings ) slide the cam out as shown,
It's always better with 2 people, as you slide it, it's a good practice to rotate it to help the lobes clear the main cam bearings.
If you get any resistance stop, rotate it, make sure it's square and try again.

Ok now the cam is out, if you've still got stuck lifters you can drive them out from underneath. if you want to re use them use a brass drift or piece of wood.

Back to the Hornets nest, this is what cam out of the Galleries, don't think it would have lasted to long

The only other problem we found was a fairly big one, on the passenger side deck face we found these scores,
Fuggered if I know what they're from or how the guy who rebuilt this engine thought it'd be ok.

They radiate from under the fire ring on the gasket to the coolant passage on one side, and between the bores on the other,
would have very likely caused a blown head gasket in short order!! :52::52:

Now it's all in pieces, Using two screwdrivers or a long jaw puller, remove the timing chain sprocket from the crank,
if like me you find burrs on the snout of the crank from the balancer, give them a clean up with some medium Emery cloth first.
(Forgot to take a pic)

I then Used a 3" micrometer to check the concentricity and sizes of the journals on the crank, they were ok,
but I was unhappy with the surface finish so it has gone with the block to the machine shop, the block is going to have the decks checked for squareness, and decked.
(More compression is always good when running straight LPG) the crank is going to be linished and the whole rotating assembly balanced, while not essential it will add to the longevity
and performance of the engine

But before I send it off.....

I once had an engine that shat itself because a casting dag came off and jammed the oil pump, breaking the pump drive shaft.
As a result I always remove any internal casting dags on an engine block, his one was pretty good, except for the oil return drains in the Valley

Again with one of my trusty die grinders,
( Did I mention how handy they are ? I used a carbide bur to remove the casting dags, and then a medium grit stone to smooth and round off the edges.

The crank and block are machined ready to go butwe've decided to have the entire reciprocating assembly balanced.

Then I found another issueCan you pick the problem ?

While getting the rods and pistons ready to take to the machine shop I found that 3 of the 8 pistons are odd, as in different weights, and design. This would have caused havoc with the balancing and could have quite possibly led to an untimely demise of our new engine, so new pistons are on their way. We're also replacing the rod bolts as some are stretched and again are of different brands.